1. Field of the Invention
This invention relates to a disposable, prefilled hypodermic syringe and to a specially designed ampul adapted for use with a separate hypodermic needle. More particularly, it relates to a hypodermic syringe having a special seal to protect the medicament from bacteria and contamination.
2. Description of the Prior Art
Ampuls for use in conjunction with hypodermic needles have been formed from resin and other plastic material which provides a resiliency or "memory" characteristic whereby the ampul resumes its original shape after compression. See, for example, U.S. Pat. No. 2,615,446 to Lingenfelter. In such prior art, covers for the ampuls are simply mechanically engaged about the neck of the ampul.
In the alternative, U.S. Pat. No. 3,524,445 to Frieze discloses a thin elastic film stretched about and cemented or heat-sealed to the bore of the ampul. Such arrangements are also shown in U.S. Pat. No. 2,757,671 to Haafkens; U.S. Pat. No. 2,388,323 to Henderson; U.S. Pat. No. 2,512,568 to Saffir; U.S. Pat. No. 2,744,527 to Barrett et. al.; and U.S. Pat. No. 3,192,925 to Cunningham. Each of such prior art seals contains an interface between the ampul and the seal which could expose the medicament to the entry of bacteria.
Other patents of general interest include U.S. Pat. Nos. 3,368,557; 3,114,369; 3,090,383; 2,771,879; 2,693,183; and 2,642,064.
The present invention differs in structure and design from the arrangements disclosed in the foregoing patents and provides the following important advantages: (a) no pre-sterilization is needed; (b) no subsequent sterilization is needed; (c) no interface to permit entry of bacteria; and (d) the ampul-syringe unit is readied immediately before introducing the needle into the tissue.